1. Field of the Invention
The present invention relates to a valve with a residual pressure indicator for a portable oxygen inhalant cylinder, which is provided for an oxygen inhalant cylinder used by a patient who has pulmonary disease or respiratory disease or carried by a doctor or rescuers at a rescue operation, and of which valve casing is provided with a residual pressure indicator at the lower half thereof which indicates a residual oxygen pressure in the cylinder (inner volume: ab. 3 l).
2. Prior Art
Recently, thanks to a medical progress there is an increasing number of patients who go out with the aid of an oxygen walker even though such patients always need the oxygen inhalants due to their pulmonary disease or respiratory disease.
In case the oxygen in the cylinder is emptied during their outing or during rescue dispatching, such patients get into difficulty in breathing and encounter a fatal danger. Therefore, in order to prevent such dangerous situations, it is necessary that the sufficient amount of residual oxygen in the cylinder is confirmed prior to leaving by means of the residual pressure indicator.
A valve with a residual pressure indicator for a portable oxygen inhalant cylinder according to the present invention has a basic construction, for example as shown in FIG. 1 or in FIG. 7.
That is, in an upper half of a valve casing 6, there is provided a valve chamber 8 which has an inlet port 9 opened at the bottom surface of the casing 6 as well as an outlet port 10 opened at the side surface thereof and also has a valve body 11 located therein. At the upper side of the valve casing 6, there is provided a handle 12 which is used for opening and closing the valve body 11, and at the lower half of the valve casing 6, there is provided a residual pressure indicator 13 for an oxygen cylinder.
As for a construction for setting the residual pressure indicator on the valve such is known in the conventional first embodiment as shown in FIG. 7.
In this embodiment, a residual pressure conduction port 50 is transversely branched off from the intermediate portion of the inlet port 9 and opened at the lower half side surface of the valve casing 6. And to the outer end portion of the residual pressure conduction port 50, a Bourdon tube pressure gauge 51 is fixedly connected in communication by means of its foot screw 51a.
Besides the oxygen inhalant application and the premised construction as described above, the conventional second embodiment as shown in FIGS. 8 and 9 has so far been placed on the market as a valve provided with a primary pressure indicator in a pressure reduction valve which is detachably connected to a liquefied carbon dioxide container for a draught beer feeder.
FIG. 8 is a plan view of the pressure reduction valve 53, in which carbon dioxide gas in the container 54 is induced to a primary pressure inlet 53a from the container valve 55 while the primary pressure is indicated by the primary pressure indicator 56, then reduced in pressure within a pressure reduction valve body 57 and discharged from a secondary pressure outlet 53b while the secondary pressure is indicated by a secondary pressure indicator 58.
FIG. 9 is a vertical sectional view of the primary pressure indicator 56 of an air pressure operational cylinder type which has a pressure receiving piston counterbalanced by a balance spring. It is fixedly secured to the side surface of the pressure reduction valve body 57 so as to project laterally by means of screws. When the primary pressure is transmitted to a cylinder chamber 59 through a primary pressure discharge pot 57a and the pressure in a container 54 gets a fully charged pressure, the piston actuates a residual pressure indicating rod 61 so as to project a residual pressure indicating ring 62 thereof a large distance outside a cover 63. As the residual pressure is decreased, the indicating ring 62 is shifted toward the cover 63 by the balance spring 64. When the residual pressure in the container has decreased to ab. 20 Kg/cm.sup.2, the indicating ring 62 enters the cover and is concealed therein.
Further, in spite of being from a different field than the third embodiment another valve is disclosed in U.S. Pat. No. 4,580,450 by the assignee of the present invention.
As shown in FIG. 10, in the side wall of a valve casing 71 of a high pressure valve 70 for a vertical elongated cylindrical container C for liquefied carbon dioxide, there is provided a vertical guide hole 72 formed as a blind hole upwardly from the lower surface 73 of the valve casing 71 over the whole of its height. In this guide hole 72, there is provided a residual quantity detecting means 74 movable in the vertical direction. The detecting means is connected to an elongated cylindrical float 76 through a rod 75. The float 76 is received in the container C movably in the vertical direction. The rod 75 is biassed downwardly by an extension spring 77 held by the valve casing 71. At the level corresponding to the residual quantity detecting means 74 outside the peripheral wall of the guide hole 72, there is provided a residual quantity indicating means 78 so as to indicate a residual quantity of liquefied carbon dioxide in the container C. The indicating means 78 is adapted to be moved vertically by the detecting means 78 through magnetic force so that the liquid level in the liquefied carbon dioxide container C can be confirmed visually with the residual quantity indicating means 78.
The conventional first embodiment shown in FIG. 7 has for its advantages large pressure-resistance as well as high accuracy for indicating a residual pressure because the residual pressure in the container is detected by a deformation of a Bourdon tube under pressure, but has for its disadvantages following problems:
(a) The Bourdon tube pressure gauge 51 has a magnifying mechanism of a gear type for magnifying a very small displacement caused by a deformation of a Bourdon tube under pressure, which serves to drive a pointer on a graduated plate in a magnified manner by making use of a pinion having fine teeth. Further, since the Bourdon tube pressure gauge 51 is small enough to be used for the small portable oxygen inhalant container 1 correspondingly, the teeth of the pinion becomes finer and weaker against a shock as the result.
In case that the teeth of the pinion become damaged when the pressure gauge 51 is shocked by its falling or its collision with other objects, the pointer is apt to be locked. Thus, in the case of using it without noticing such trouble, the pointer is kept indicating a high pressure even though a residual pressure in the container has decreased to a large extent. As a result, in spite of the confirmation of enough residual pressure of oxygen by the patient before outing, it is possible that the patient gets into a fatal danger because the oxygen is almost exhausted during an outing.
(b) Since the Bourdon tube pressure gauge 51 is secured to the valve casing 6 in an outward projecting manner, it is apt to be broken by a shock caused by its falling or its collision with other objects. In such a case, it is also possible that the patient gets into a fatal danger because the oxygen escapes completely from the container through the breakage portion.
Even though the patient gets out of such danger, the Bourdon tube pressure gauge 51 is always in danger of breakage by collision with other objects because it projects outside the valve casing 6.
The Bourdon tube pressure gauge 51 of the conventional first embodiment as shown in FIG. 7 can be replaced with the primary pressure indicating means 56 of the conventional second embodiment 2 as shown in FIGS. 8 and 9. In the combined construction of these first and second conventional embodiments, since it is adapted to transmit the movement of the piston 60 directly to the residual pressure indicating rod 61, it has such advantage as the above-mentioned problem (a) can be solved. However, it still has the problem (b) as well as the following problems. Even though the residual pressure indicating ring 62 indicates ab. 20 Kg/cm.sup.2 at the position near the entrance of the cover 63, it is still difficult to know a residual pressure in the container when the ring 62 is outside the cover or within the cover 63.
On the other hand, the third conventional embodiment is applied to a relatively large container C for liquefied carbon dioxide in an entirely different field from the present invention. And since the residual quantity indicating means is adapted to be moved correspondingly by the vertical movement of the float 76, it can't be applied to the small-sized light gas cylinder which is charged with compressed oxygen for an oxygen inhalation. Further, also in this third conventional embodiment, since the residual quantity indicating means 78 is attached to the valve casing 71 in an outwardly projecting manner, it is impossible to avoid the risk of the breakages of the indicating means 78 by its falling or by its collision with other objects.